Debt (Senior Notes) (Details) (USD $)	3 Months Ended		6 Months Ended		0 Months Ended	3 Months Ended	6 Months Ended	12 Months Ended	0 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2012	Jul. 02, 2011	Jun. 30, 2012	Jul. 02, 2011	Jan. 17, 2006 6.125% Notes, Payable January 15, 2016 [Member]	Mar. 31, 2012 6.125% Notes, Payable January 15, 2016 [Member]	Jun. 30, 2012 6.125% Notes, Payable January 15, 2016 [Member]	Dec. 31, 2009 6.125% Notes, Payable January 15, 2016 [Member]	Apr. 16, 2012 7.20% Senior Notes, Payable April 15, 2012 [Member]	Jun. 30, 2012 7.20% Senior Notes, Payable April 15, 2012 [Member]	Dec. 31, 2011 7.20% Senior Notes, Payable April 15, 2012 [Member]	Dec. 31, 2002 7.20% Senior Notes, Payable April 15, 2012 [Member]
Debt Instrument [Line Items]
Aggregate principal amount of debts					$ 900,000,000							$ 400,000,000
Interest rate percentage							6.125%			7.20%	7.20%
Notes payable, maturity date							Jan. 15, 2016			Apr. 15, 2012
Increase in interest rate from rating agency downgrade							0.25%
Maximum increase in interest rate per agency from rating agency downgrade							1.00%
Aggregate amount of increase in interest rate from rating agency downgrade								0.75%
Aggregate amount of decrease in interest rate from rating agency downgrade						0.50%
Increase in interest expense per quarter for .25% increase in notes per $100,000 of outstanding notes	18,844,000	25,760,000	41,342,000	52,355,000	63
Incremental increase in outstanding notes					100,000
Remaining outstanding senior notes repaid											63,730,000
Repurchase price as percentage of principal amount of senior notes											102.72%
Company repaid principal amount									336,270,000
Debt instruments interest accrued									$ 12,106,000